1. Field of the Invention
The present invention relates to a method for patterning a thin film on a substrate, and more particularly to a method for patterning a thin film on a substrate using a partially developed anti-reflective coating (ARC) layer.
2. Description of Related Art
In material processing methodologies, pattern etching comprises the application of a thin layer of light-sensitive material, such as photo-resist, to an upper surface of a substrate that is subsequently patterned in order to provide a mask for transferring this pattern to the underlying thin film on a substrate during etching. The patterning of the light-sensitive material generally involves exposure by a radiation source through a reticle (and associated optics) of the light-sensitive material using, for example, a photo-lithography system, followed by the removal of the irradiated regions of the light-sensitive material (as in the case of positive photoresist), or non-irradiated regions (as in the case of negative resist) using a developing solvent. Moreover, this mask layer may comprise multiple sub-layers.
Once the pattern is transferred to the underlying thin film, it is essential to remove the mask layer while not damaging the material properties of the underlying thin film. For example, the thin film may comprise a low dielectric constant (low-k, or ultra-low-k) dielectric film that may be used in back-end-of-line (BEOL) metallization schemes for electronic devices. Such materials, which may include non-porous low-k dielectrics as well as porous low-k dielectrics, are susceptible to damage, e.g., degradation of dielectric constant, water absorption, residue formation, etc., when exposed to the chemistries necessary for removal of the mask layer and its sub-layers. Therefore, it is important to establish pattern transfer schemes that reduce the potential for damaging the underlying thin film when forming such a pattern and removing the necessary mask layer(s).